My research tends to be very interdisciplinary, spanning
behavioral psychology, systems neuroscience, computational modeling,
even comparative neuroscience and human evolution.
Dr. Mike Gazzaniga's publications on split brain patients inspires
my research, wondering: if the two hemispheres can largely operate on their own,
then what does our singular consciousness mean? How do two different hemispheres
talk to each other?
Current Research Projects
I am currently involved in three research projects
with my advisor, Garrison Cottrell.
They are:
-
Measuring lateralization -
Currently, lateralized function
in the brain is measured behaviorally, through brain damage, or through
visible differences in neuroimaging (ERP: different waveforms; fMRI: difference
in number or intensity of activated voxels)
We are currently using multivariate approaches to see:
- Relationships between different asymmetries in the brain. When
one part of the brain is asymmetric, are any others areas always
asymmetric too?
- Representational similarity analysis (RSA) - forget whether
the two sides are active to the same level. Is the pattern of activations
across all stimuli similar on the left and right sides, or are they
computing different things?
-
"Differential Encoding"
(COGSCI 2012,
2014)
- We use a simple neural network modeling
technique (autoencoder PDP models) to
to relate long-range lateral connections within visual areas of the brain
to spatial frequency processing. We then use this model to account
for differences in how the left and right sides of the brain
process visual information across numerous behavioral experiments.
Current project: our model predicts that it's more about contour processing,
and not necessarily low frequency information,
that differs between the hemispheres. We're modeling contrast balancing
experiments--where contours are visible, but low frequencies are attenuated--to
see if our model can account for these data that other models may not.
Representative posters and talks:
- COGSCI 2014: Developmental model (Slides)
- COGSCI 2012: Basic model (Poster)
-
Time delays and development (COGSI 2013) - We use a recurrent neural network in time
to show that effects of time delays, when predictable, are highly over-stated--they
can be overcome through predictive learning, one of the fundamental features of the brain.
In this project, we argue that unreliable time delays cannot be overcome by
such means, suggest that unreliable delays exist early in mammalian development,
and argue that this effect is exacerbated more in humans than any other animal.
Current project: The Ringo model never actually tested whether
varying interhemispheric projections affects lateralization. We are testing
this by using RSA--representational similarity analysis--to see whether
information in each hemisphere is more or less similar as we manipulate
connections between them.
Representative posters and talks:
Future Research Projects
I am currently applying for post-doctoral fellowships. Proposed research projects include:
Computing the human corpus callosum - The human corpus callosum is
composed of many tiny fibers that are hard to view; they quickly disintegrate after death,
and require an electron microscope to see. However, the prevalence of these fibers
affects not only how we think, but how researchers interpret people's brain scans, particularly
structural scans that tell us about the brain's long-distance connections (DTI).
In this project, I plan to use animal data (electron microscope, with small fibers) and
human data (light microscope) to estimate the true numbers of fibers in the human corpus callosum
across the lifespan. I then hope to use this information to help interpret human
structural brain scans (DTI).
Past Research Projects
-
Interhemispheric connectivity across species (unpublished) - It has been argued that the hemispheres
are asymmetric particularly in humans because our hemispheres are more independent than in other
mammals. We hypothesize that the opposite must be true - in order for the two sides to do
different things, they must be able to talk with each other.
In this project, we show that a previous reports of decreased connectivity between the hemispheres
in large-brained animals were based on incorrect assumptions. Using more data from the literature,
we show that interhemispheric connections are as important, and probably
more important, than the average connection between two parts of the brain.
Representative posters and talks:
Dissertation
I completed my dissertation defense in May, 2014.
My dissertation committee, along with the areas of their expertise that
intersect with my projects, includes:
- Garrison Cottrell--research advisor, expertise in autoencoder neural network models and computational modeling of cognition
- Marta Kutas--department advisor, expertise in hemispheric asymmetry and cognition
- Steven Hillyard--expert in spatial attention, has worked in local/global processing
- Virginia de Sa--Expert in multi-modal neural network modeling and computational models
- Katerinal Semendeferi--Expert in local circuitry
- Terry Jernigan--Expert in white matter connectivity